From a8be4bb61502d8cb33378e6587c8df22a32ec516 Mon Sep 17 00:00:00 2001
From: Lonami Exo <totufals@hotmail.com>
Date: Thu, 17 May 2018 10:42:20 +0200
Subject: [PATCH] Fix catch_up may use None state

---
 telethon/telegram_client.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/telethon/telegram_client.py b/telethon/telegram_client.py
index 3b0fd464..4f1ae2aa 100644
--- a/telethon/telegram_client.py
+++ b/telethon/telegram_client.py
@@ -2427,6 +2427,9 @@ class TelegramClient(TelegramBareClient):
 
     def catch_up(self):
         state = self.session.get_update_state(0)
+        if not state:
+            return
+
         self.session.catching_up = True
         try:
             while True: